In a hydraulic cylinder system used in a maneuvering system of an aircraft, a vehicle and the like, a configuration provided with electric redundancy has been employed (See Patent Literature 1, for example). And, in the hydraulic cylinder system having the prior-art configuration, a large number of coils need to be provided in a motor of a driving system in order to realize high electric redundancy. With this, the size of the motor of the driving system increases, and thus creates a problem that the size and the mass of the hydraulic cylinder system itself increase.